Synthesis and some properties of light lanthanide complexes with 4,4′-bipyridine and dibromoacetates

Journal of Thermal Analysis and Calorimetry, Dec 2013

In this study, new complexes with formulae: Ce(4-bpy)(CHBr2COO)3·H2O, Ln(4-bpy)0.5(CHBr2COO)3·2H2O (where Ln(III) = Pr, Nd, Sm; 4-bpy = 4,4′-bipyridine) and Eu(4-bpy)(CHBr2COO)3·2H2O were prepared, and characterized by chemical and elemental analyses, and IR spectroscopy. The way of metal–ligand coordination was discussed. They are small crystalline. The complexes of Pr(III), Nd(III), and Sm(III) are isostructural in group. Conductivity studies (in methanol, dimethylformamide, and dimethylsulfoxide) were also performed and described. The thermal properties of complexes in the solid state were studied using TG–DTG techniques under dynamic flow of air atmosphere. TG–MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolyses of Ce(III) and Sm(III) complexes in dynamic flow of air atmosphere.

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Synthesis and some properties of light lanthanide complexes with 4,4′-bipyridine and dibromoacetates

Thermal study 0 A. Czylkowska 0 0 A. Czylkowska (&) Institute of General and Ecological Chemistry, Lodz University of Technology , Lodz, Poland In this study, new complexes with formulae: Ce(4bpy)(CHBr2COO)3 H2O, Ln(4-bpy)0.5(CHBr2COO)3 2H2O (where Ln(III) = Pr, Nd, Sm; 4-bpy = 4,40-bipyridine) and Eu(4-bpy)(CHBr2COO)3 2H2O were prepared, and characterized by chemical and elemental analyses, and IR spectroscopy. The way of metal-ligand coordination was discussed. They are small crystalline. The complexes of Pr(III), Nd(III), and Sm(III) are isostructural in group. Conductivity studies (in methanol, dimethylformamide, and dimethylsulfoxide) were also performed and described. The thermal properties of complexes in the solid state were studied using TG-DTG techniques under dynamic flow of air atmosphere. TG-MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolyses of Ce(III) and Sm(III) complexes in dynamic flow of air atmosphere. - This article is a continuation of our earlier research on lanthanide complexes with 4,40-bipyridine (4-bpy) and halogenoacetates. The rare earth compounds containing halogenoacetates have been studied by many authors. They consider mainly the metalligand coordination and magnetic behavior. The mixed-ligand complexes of some lanthanides with 2,20- or 4,40-bipyridine and chloroacetates are known, but with only scant information concerning their thermolysis. Several notes of discussed compounds containing halogenoacetates have been summarized in [13]. Our resent investigation related to mixed-ligand lanthanide complexes with 4-bpy and di- or trichloroacetates. We obtained compounds of general formulae: Ln(4-bpy)n (CHCl2COO)3 mH2O [1, 2, 47] and Ln(4-bpy)n(CCl3 COO)3 mH2O [1, 3, 8, 9] in series Ln(III) = Y, La ? Lu (without Pm). They were characterized by elemental analysis, molar conductivity, and IR spectra. Their thermal behaviors were also studied. The way of metalligand coordination was discussed. The chloroacetate groups link with rare earth elements in many different ways. In case of La(III) [4] and Sm(III) [5] compounds, dichloroacetate groups coordinate as chelating tridentate and bridging ligands, and in other compounds [2] as bidentate chelating and monodentate ions. In all compounds 4-bpy joins with lanthanide by one nitrogen atom (only in complexes Er(III), Tb(III), and Lu(III), also half molecule of 4-bpy lies in outer coordination sphere [2]). In the literature, there is not much information about lanthanide complexes with bipyridine isomers and dibromoaceates. Thermal studies of compounds with empirical formulae Ln(2-bpy) (CHBr2COO)3 mH2O where Ln(III) = Nd, Er were characterized in [10]. In one of our previous articles, we have described preparation and some behaviors of La(III) and Y(III) complexes with title ligands [11]. In this work, we present the synthesis, some physicochemical properties, and thermal studies of new compounds of light rare earth elements with 4-bpy and dibromoacetates. These studies of lanthanide(III) complexes with 4,4-bipyridine and halogenoacetates allow us to determinate the influence on the kinds of forming complexes, their properties, and thermal decomposition dependent on the type of halogen atoms in carboxylates. Materials, synthesis, and analysis 4,4-bipyridine, CHBr2COOH, Ln2O3 (where Ln(III) = Nd, Sm, Eu), Pr6O11, Ce(NO3)3 6H2O, dimethylsulfoxide (DMSO), dimethylformamide (DMF), and methanol (MeOH) (anhydrous) p.a. were obtained from Aldrich and Lab-Scan. Water solutions of metal(III) dibromoacetates were prepared by adding 2 mol L-1 dibromoacetic acid to freshly precipitated hydroxides (or freshly precipitated cerium(III) carbonate) in ca. stoichiometric quantities. (in temperature B18 C, because lanthanide dibromoacetates in solution are relatively unstable; in presence of 4-bpy their stability arise). The mixed-ligand complexes were synthesized by reaction of freshly obtained solutions of appropriate Ln(III) dibromoacetaes with solutions of 4-bpy (pH * 5). The molar ratio of M(III):4-bpy was 1:2. Solution of 4-bpy in 31.3 mL of 96 % v/v ethanol (12.4 mmol) was added to 8.7 mL of water solution of Ln(III) dibromoacetates (6.2 mmol). The products were washed in 40 % v/v ethanol and then in ethanol and diethyl ether mixture (1:1). All compounds were dried in open air. The contents of metal(III) ions in obtained solutions were mineralized and determined by EDTA titration. The carbon, hydrogen, and nitrogen contents in the prepared complexes were determined using a Carbo-Erba analyzer with V2O5 as an oxidizing agent. Methods and instruments IR spectra were recorded using a NICOLETT 6700 Spectrometer (4000400 cm-1 with accuracy of recording 1 cm-1) using KBr pellets. Molar conductance was measured on conductivity meter of the OK-102/1 type equipped with an OK-902 electrode at 25 0.5 C, using 1 9 10-3 mol L-1 solutions of complexes in methanol, dimethylformamide, a (...truncated)


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A. Czylkowska. Synthesis and some properties of light lanthanide complexes with 4,4′-bipyridine and dibromoacetates, Journal of Thermal Analysis and Calorimetry, 2013, pp. 989-995, Volume 114, Issue 3, DOI: 10.1007/s10973-013-2952-3